The present invention relates to a ski boot made of hard synthetic resin and having improved fit to a wearer's foot.
Conventional ski boots made of hard synthetic resin are roughly classified into two major types, i.e. a rear-entry type and a front-entry type. One example of the rear-entry type ski boot is disclosed in Japanese Patent Opening Sho. 62-112503. The ski boot of this earlier application is made up of a sole, a front shell formed in one body with the sole and a rear shell pivoted to the front shell and tiltable rearwards for entry of a wearer's foot. In one example of the front-entry type, the ski boot is made up of a sole, a rear shell formed in one body with the sole and a front shell made up of left and right pieces which are respectively turnable sideways for entry of a wearer's foot. In another example of this type, a tongue is arranged between left and right pieces and turnable forwards for entry of wearer's foot.
The conventional ski boot of the rear-entry type, the boot cannot sufficiently hold the wearer's foot when the wearer tilts his leg rearwardly.
The human foot is generally largest just in front of the shank and the size of the opening formed by turning of the corresponding shell should be large enough to allow free passage of the portion of the foot at the entry of the wearer's foot. This naturally requires a large construction of the boot. In addition, foot sizes vary greatly from wearer to wearer and a ski boot must be large in construction so that one boot size can span as many foot sizes as possible. These factors concur to make the size of a ski boot unduly larger than necessary for accommoding wearer' feet. Because of such an unduly large construction, a ski boot generally does not fit a wearer's foot well and, as a consequence, cannot provide reasonable hold on the foot in particular when the wearer's leg is moved significantly.
In order to improve the fit to a wearer's foot, it has been proposed to use an inner boot made of soft material such as sponge. More specifically, such an inner boot is inserted into a ski boot in order to fill a space between the shells and a wearer's foot. A pad is often additionally provided within the ski boot in contact with the instep of the wearer's foot. Such a pad can be pressed against the instep by means of a cable or a screw which is operable from outside the ski boot. The Achilles' tendon may be fastened by a proper tensioner arranged on the rear face of the ski boot.
However, these expedients provide local fastening of the wearer's foot only, admittedly somewhat better than no expedients. The problems of poor fit and insufficient hold on the wearer's foot remains due to the absence of overall fastening. In addition, conventional tensioners used for this purpose are generally complicated in construction.